Compressor shut-off valve mechanism



Jan.9, 1940. -w. F." BOLDT COMPRESSOR SHUT-OFF VALVE MECHANISM Filed July 5. 193a ZShe'ets-Sheet 1 l m. Y I 3 M WE o mo n E H w W x i e m w. w in Q w W w. FLBOLDT 2,186,320

COMPRESSOR SHUT-OFF VALVE MECHANISM I Filed July 5, 193a INVENTOR RNER Bo'LD'T Jan. 9; 1940.

Patented Jan. 1940 UNITED STATES ooMPnEsson-snUT-orr VALVE MECHANISM Werner F. Boldt, Clayton, Mo.,' assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application July 5, 1938, Serial No. 217,485

12 Claims. (01.303-11) My invention relates to valve mechanism. and

more particularly tovalve mechanism .Ior shutting ofi the intake of a compressor tounload it under certain conditions.

One of the objects of my invention is to provide an improved shut-oil valve for the intake of a compressor which will be automatically closed when the pressure in the compressor receiver reaches 'a maximum predetermined value and 1 which will be positively reopened each time air under pressure is used from the receiver by a fluid-actuated system associated therewith.

Another'object of my invention is to provide means associated with the shut-oi! valve mechanism for permitting fluid to be supplied to the compressor intake in the event the pressure of the fluid in the receiver should drop below a predetermined. minimum'value during the time fluid is not being used from the receiver by the fluid g0 pressure-actuated system.

Other objects of my invention will become apparent from thefollowing description taken in connection with the accompanying drawings in which Figure 1 is a view of a compressor, a re- 25 ceiver therefor, and a fluid-actuated system showing my improved compressor intake shutofi valve mechanism associated therewith; Fig- 'ure 2 is a longitudinal cross-sectional view of the valve mechanism taken on the line 22 of Figure 1; and Figures 3 and 4 are cross-sectional views taken on the lines 38 and 44, respectlvely, of Figure 2.

Referring to the drawings in detail, the compressor I, with which I have illustrated my shutoff valve mechanism as being associated, is of the rotary type having a stator 2 and an eccentric-ally mounted rotor 3 provided with a plurality of blades 4 (oneonly being shown). The stator has an intake port 5 and an outlet port 6,

40 connected to a pressure tank 8 by means of a conduit 9, the oil dome and pressure tank both I being considered as the receiver of the com- 'pressor. The outlet of the compressor has associated therewith a check valve Ill for preventing back flow of the compressed fluid and associated with the outlet of the dome is another check valve II. The pressure tank 8 is shown as connected by a conduit l2 with a fluid motor I8 which may be employed to operate any mechanism desired, as .for example,'a braking mechanism. The fluid pressure employed to actuate the fluid motor is controlled by a valve I4 in conduit l2, this valve being shownas a hand valve but it is understood that other valve mechanisms the latter opening into an oil dome l which is such as a foot control valve may be employed if I desired.

In compressors of the type described which are of well-known construction it is desirable to automatically prevent the compressor from compressing fluid after the fluid in the receiver has been placed under a predetermined maximum pressure. This is'best accomplished by shutting oil the intake port so the air or other fluid which is being compressed by the compressor is not permitted to enter the compressing chamber. It is also desirable that the intake port not only be automatically closed at the proper time but that it also be reopened whenever the pressure in the receiver drops. I i

The valve mechanism comprises a casing 18 which is provided with parallel bores ii and i8, the bore I8 being formed with two chambers l9 and 20 connected by a passage 2| and bore I! being formed with two chambers 22 and23 con- 20 nected by a passage 24. The casing is also provided with an inlet 25 which connects with chambers l8 and 22 and with an outlet passage 26 which communicates with chambers 20 and 23. The inlet has associated therewith an air 25 cleaner 2! and the outlet is adapted to communicate with the intake port 5 of the compressor when the valve mechanism is mounted on the compressor. The chamber I8 has loosely mounted therein a slidable valve member 28 which is 30 adapted to cooperate with a seat 28 for closing passage 2! between chambers l9 and 28. The chamber l9 at the rear of the valve member 28 is connected to the dome of the compressor by a conduit 30. Communication between the conduit and the chamber at the rear of the piston is controlled by a valve 3| biased against its seat by spring 32 interposed between the valve element and the member 83 supported by a hollow plug of the casing. Within the chamber 28 is a piston carries a rod 35 extending through passage 2| to a point spaced from valve member 28 when this valve member is in the position shown. A spring 38 surrounds the rod and is interposed 5 between the valve member 28 and the piston 34 and normally tends to hold the valve member 28 unseated. There is also provided a spring 81 for maintaining piston 84 at the right end of chamber 28. The right end of the chamber 28 is connected by a conduit 88 with conduit l2 at a point between the control valve I4 and fluid motor l3.

Within chamber 23 is a slidable valve member 39 which adapted to cooperate with a seat 48 to 1 84 which close the passage 2 between chambers 22 and 23. The valve member is biased to open position by spring 4| interposed between the valve member and a cap 42 closing the end of chamber 22. The right end of chamber 23 is connected by a conduit 43 to conduit 9 leading from the oil dome to the tank.

The springs of the valve mechanism may be designed to cause the valve mechanism to operate to maintain any predetermined maximum pres-v sure in the receiver which is desired. In the valve mechanism shown, the spring 32 is so designed that fluid under pressure will not be admitted into the chamber at the rear of the valve member 28 until the fluid. pressure in the dome reaches one hundred pounds per square inch. The spring H is so designed that it will unseat the valve member 39 when the air pressure acting on it from the receiver is ninety pounds per square inch. The spring 36 is a light spring, only being strong enough to keep valve member 28 unseated if there is no pressure acting on this-member tending to move it to closed position. The spring 31 is also a relatively light spring being only strong enough to normally bias piston 34 to the right end of chamber 20 when no pressure is acting on the forwardportion of the piston.

In operation, when the parts of the valve mechanism are in the position shown, air will be free to be drawn into the intake port of the compressor and be compressed thereby and forced out into the oil dome and into the tank.

When the pressure in the tank exceeds ninety 1 pounds per square inch, there will be sufllcient Pressure acting on valve member 39 to move it to the left and close passage 24. This will not prevent the compressor from continuing to operate under load'since passage 25 leading to the intake is still in communication with passage 25 by means of passage 2!. When the pressure in the oil dome and the tank reaches one hundred pounds per square inch, valve element 3| will be unseated and pressure from the dome will enter the chamber at the rear of the valve member 28. When sufiicient pressure is present in this chamber to overcome the biasing action of the weak spring 36 (this pressure need not be greater than a few pounds per square inch), the valve member will be moved against seat 29, therebv preventing air from being drawn into the compressor. The compressor will now be unloaded and will run idle.

It is to be noted that the valve member 28 is so associated with its seat and the passage 26 leading to the intake of the compressor that the vacuum of the compressor will assist in holding the va ve member 28 seated once it is moved to its seat by suiflcient pressure acting thereon. This a rangement insures thatthe intake to the compressor will be positively closed against leakage,

If. after the fluid in the dome and tank has been brought up to its maximum pressure and the compressor has been unloaded, fluid should be used to operate the fluid motor I 3 by operation of the control valve it, there will be a drop in the pressure in the tank and dome. This, however, will be immediately replaced by the compressor since the pressure admitted to the fluid motor is also effective through conduit 38 to move piston 34 to the left and against spring 31 and cause rod 35 to engage valve member 28 and disengage it from seat 29. The intake of the compressor is again connected to-the atmosphere. After the compressor has again restored the pressure in the dome and tank to its maximum, the valve mechanism will operate in a manner already described to prevent air from being drawn into the compressor intake.

There may be conditions where fluid motor l3 may not be operated over a long period of time and because of a small leak in the compressor dome or tank or the connecting conduits, the receiver pressure may drop. In order to insure that the pressure in the tank and dome under these conditions will be maintained at a reasonable minimum value, valve member 39 and associated structure, already described, has been incorporated into the mechanism. As soon as the pressure in the tankreaches the minimum value of say eighty pounds per square inch, spring 4| will function to move valve member 39 to the right, thereby opening passage 24. The passage 26 is now in communication with passage 25 leading to the atmosphere and the compressor may now begin to operate. As soon as the compressor begins to operate, the vacuum effective on the valve member 28 tending to hold it seated will be broken and the valve member will be moved to the left under the action of spring 36 and air may pass through the passage 2|. When the tank pressure reaches suflicient value, valve member 39 will be-reseated but the compressor will continue to operate until the pressure in the dome and tank again reaches the maximum of one hundred pounds per square inch when the valve member 28 will be closed thereby unloading the compressor.

From the foregoing description it is apparent that I have constructed an'eflicient and reliable valve mechanism. The valve member 28 is operable by very small pressures because no packing cups are employed to cause increased frictional resistance. The mechanism insures that the receiver pressure will be maintained above a minimum value under all circumstances.

Being aware of the possibility of modifications in the particular structure herein described without departing irom the fundamental principles of. my invention, I do not intend that its scope be limited except as set forth by the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a fluid pressure-actuated system adapted to be operated by fluid pressure from the receiver, valve means comprising a movable valve member for controlling the intake, means for automatically moving said valve -member to closed position when the pressure in the receiver is a predetermined value, a movable member for engaging the valve member to move it to a position to open the intake, a spring for normally biasing the member to an inoperative position independently of the valve, a fluid motor for actuating said movable member, and means for operating said fluid motor by pressure from the fluid pressure-actuated system when the latter is operated.

2. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a fluid pressureactuated system adapted to be operated by fluid pressure from the receiver, valve means comprising a movable valve member for controlling valve closed.

ansaaao the intake and when in closed position being so maintained by the suction of the compressor,

3. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected .to the exhaust port, a casing provided with a passage leading to the intake, means comprising a movable valve member for closing the passage when the pressure in the receiver is a predetermined value, said valve member being so associated with theintake that suction of the compressor will assist in holding the valve member seated, means forming a second passage to the intake, a valve for said second passage, means for maintaining said last named valve closed by the pressure from the receiver, and means for causing said last named valve to assume open position when the pressure in the receiver drops below the pressure necessary to maintain said 4. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, valve means comprising a movable valve member for controlling the intake, means for automatically moving said valve member to closed position when the pressure in the receiver is a predetermined value, said valve member being so associated with the intake that suction of the compressor will assist in holding the valve member seated, a by-pass around said valve means, a valve for said by-pass, and means for causing said last named valve to be opened when the pressure in the. receiver drops to a point below the predetermined value.

5. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaustport, a fluid pressure receiver connected to the exhaust port, a casing provided with a passage leading to the intake, means comprising.

a movable valve member for closing the passage when the pressure in the receiver is a predetermined value, said valve member being so associated with the intake that'suction of the compressor will assist in holding the valve member seated, means forming a second passage to the.

intake, valve means including a movableelement for controlling the second passage, a spring for biasing the valve element to closed position, and means for moving said valve element to closed position by pressure from the receiver, said valve element being opened by the spring when the pressure in the receiver drops to a value below the predetermined pressure.

6. In apparatus of the class described, a fluid compressor provided with an intake port and an exhat t port, a fluid pressure receiver connected to the exhaust port, a casing provided with a passage leading to the intake and having associated therewith a valve seat. meanscomprising a movable valve member for cooperating with said seat, a spring for biasing the valve member ofl its seat, means for automatically seating said valve member when the pressure in the receiver is a predetermined value, said valve member and seat being so associated with theintake that suction of the compressor will assist in holding the valve member, seated, and means independent of the valve member and operable by a drop in pressure in the receiver below the predetermined value for connecting the intake to the source of fluid for the compressor, said valve member being permitted to open under the action of its spring when the suction of the compressor is not effective thereon.

7. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a fluid pressure-actuated system adapted to be operated by fluid pressure from the receiver, ,valve means comprising a movable valve member for controlling the intake, means for automatically moving said valve member to closed position when the pressure in the receiver isa predetermined value, said valve member being so associated with the intake that suction of the compressor will assist in holding the valve member seated, means for causing said valve member to be unseated by fluid pressure from the fluid pressure-actuated system when it .is operated, and means independent of the valve means for permitting fluid to enter the intake of the compressor when the fluid pressure in the receiver drops below the predetermined pressure.

8. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a fluid pressure-actuated system adapted to be operated by fluid pressure from the receiver, valve means comprising a movable valve member for controlling the intake, means for automatically moving said valve member to closed position when the pressure in the receiver is a predetermined value, said valve member being so associated with the intake that suction of the compressor will assist in holding the valve member seated, means for causing said valve member to be unseated by fluid pressure from the fluid pressure-actuated system when it is operated, and means independ cut of the valve means for permitting fluid to enter the intake of the compressor when the fluid pressurein the receiver drops below the predetermined pressure, said last named means comprising a valve-controlled passage having a valve element acted on by fluid pressure from the receiver and a spring for'biasing the valve element toward open position.

9. In apparatus of the class described, a fluid compressor provided with an intake port and an.

exhaust port, a fluid pressure receiver connected to the exhaust port, a fluid pressure-actuated system adapted to be operated by fluid pressure from the receiver, a casing provided with a passage leading to the intake, means comprising a movable valve member for closing the passage when the pressure in the receiver is a predetermined value, said valve member being so associated with the intake that suction of the compressor will assist in holding the valve member seated, means forming a second passage to the intake, 9.

valve'for said second passage, means for inaintaining said last named valve closed by the predetermined pressure in the receiver. means for causing said last named valve to assume .open

position when the pressure in the receiver drops below the predetermined value, and means'operable by fluid pressure when the fluid pressure- 'to close the passage by a low pressure, means for subjecting said valve member to a fluid pressure from the receiver only when the pressure of the fluid in the receiver is above a predetermined value, said predetermined pressure being above that necessary to move the valve member, means forming a second passage to the intake, a valve for said second passage, means for maintainingsaid second named valve closed when the pressure in the receiver is above a predetermined value but below the first named predetermined value, and means for causing said last named valve to assume open position when the pressure in the receiver drops below the pressure necessary to maintain said valve closed.

11. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a casing provided with a passage leading to the intake, a movable valve member in said casing for closing the passage, a light spring for biasing the valve member open aiaaaao but permittingthe valve to be closed by a low pressure, means comprising a pressure valve for permitting said valve member to be subject to a fluidpressure from the receiver only when the pressure of the fluid in the receiver is above a predetermined value, means forming a second passage to the intake, a valve for said second passage, means for maintaining said second named valve closed when the pressure in the receiveris above a predetermined value but below the first named predetermined value, and means for causing said last named valve to assume open position when the pressure in the receiver drops below the pressure necessary to maintain said valve closed.

12. In apparatus of the class described, a fluid compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a casing provided with a :passage leading to the intake, a movable valve member in said casing for closing the passage, a light spring for biasing the valve member open but permitting the valve to be closed by a low pressure, and means comprising a pressure valve WERNER F. BOLDT. 

